Aircraft airframes typically comprise a plurality of frames (or formers) and longerons (or stringers/stiffeners). The frames are typically laterally spaced from one another and arranged perpendicular to the longitudinal axis of the aircraft. The primary purpose of formers is to establish the shape of the fuselage and reduce the column length of the longerons. The longerons are typically elongate members which are attached to the frames and are arranged parallel to the longitudinal axis of the aircraft. The longerons support the aircraft skin and, in use, transfer aerodynamic loads acting on the skin onto the frames.
It is desirable that aircraft airframes are produced to be within very tight tolerance bounds.
Production of an aircraft airframe typically comprises producing two or more separate airframe sections (for example, a fore fuselage section, an aft fuselage section, and a tail section), and subsequently attaching those sections together.
It tends to be very difficult to produce separate airframe sections with a sufficient level of precision to allow for easy assembly of the airframe. Lengthy and expensive shimming processes may be required to fill gaps between the airframe sections when those sections are attached together.
Production of a section of an aircraft airframe typically involves the use of airframe assembly tools designed to support airframe components while they are being worked on and to locate different components together in the correct relative positions during airframe assembly. Traditionally, each different assembly process has required at least one dedicated assembly tool, which is produced specifically for a given set of components and which is designed to support the components in a particular manner so that assembly operations can be carried out without interference from the tool. Such assembly tools are manufactured to exacting standards.
A conventional assembly tool comprises a rigid metal jig whose framework is constructed from welded box section steel. A plurality of pick-up devices is mounted on the framework for carrying the aircraft components during the assembly process, and these too are conventionally produced from welded steel parts.
EP 1 230 124 discloses such an assembly tool.